Founding year: Wikidata. First post office: 1931.The full story ↓
History grade
What drives South Beloit’s History grade
On its age, its old homes and the National Register, South Beloit is more historic than 21% of U.S. towns, #621 of 768 in Illinois. Its share of homes from before 1940 holds the grade up; its age pulls it down.
C−
HistoryA character grade: shown, never part of South Beloit’s overall grade.
Few Illinois towns list much on the Register (a typical Illinois town has 0.5 per 10,000 residents, the U.S. 2.4), so South Beloit’s 0.0 sits below most of its state (28% of Illinois towns have fewer) while its 0 listings outnumber those of 23% of U.S. towns.
How sure. Graded on any two of the three inputs instead, the letter would range from D to C+. The pre-1940 share is a Census survey estimate (±5.7 points). Two sources give 1917.
Founding year: Wikidata (other dates in Quick answers). Homes: Census ACS 2020–24. National Register: National Park Service, May 2026 list; each listing counted once (boundary changes and added documentation belong to their listing), and a historic district counts its contributing buildings. How TownRatings grades history →
What stands out about South Beloit’s past
Read from the archive, the National Register and the record. The page puts what stands out first.
What is now South Beloit was previously full of natural resources such as copper, lead, and bog iron. Buff and blue limestones were plentiful everywhere in Winnebago County, with limestone forming the banks of the Rock River and Turtle Creek. The buff limestone gave the first settlers material for their houses and public buildings, some of which can still be seen in Rockford, Rockton, and Beloit/South Beloit. The older homes in South Beloit had 18–20-inch-thick (46–51 cm) basement walls of this limestone. The South Beloit area has a thick deposit of sand, and industries were built here because of its unusually fine quality. A fine quality of clay was also found in the state line area.
In 1917, according to Wikidata. South Beloit’s post office opened in 1931, and the census of 1920 counted 1,436 people here.
How does South Beloit rank for history?
South Beloit is more historic than 21% of U.S. towns, #621 of 768 in Illinois. The History grade combines the town’s founding era, the share of homes built before 1940 and its National Register listings. It’s a character grade, so it isn’t part of the overall grade. How it works.
How old are the homes in South Beloit?
13% of South Beloit’s homes were built before 1940 (Census estimate, ±5.7 points), against a typical 11% for an Illinois town; the median home was built in 1991.
Founding dates: Wikidata, Wikipedia, the U.S. post office records of Blevins & Helbock (CC0) and the Census. Homes by year built: Census ACS 2020–24. National Register of Historic Places: National Park Service (list of May 22, 2026). Old photos, postcards and papers: Wikimedia Commons, the Library of Congress and other public archives, credited on each item’s page. Maps: U.S. Geological Survey historical topographic maps (via Esri) and Sanborn fire-insurance maps (Library of Congress). History text and census tables: Wikipedia (CC BY-SA 4.0). Places that used to be: USGS Geographic Names Information System (2021).
From Wikimedia Commons (9), Wikipedia, U.S. Geological Survey historical maps, U.S. Census counts (via Wikipedia), the US Post Offices dataset (Blevins & Helbock) and the USGS Geographic Names Information System. Archive images are copied here with their credits and licenses, shown on each photo’s page. Refreshed monthly.
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